The achievement of complete development at the end of adolescence was suggested by Freud, Piaget, and Binet among others. Research in Positive Adult Development questions not only that development ceases after adolescence, but also the notion of decline after late adolescence postulated by many gerontologists. Positive development does occur during adulthood. Recent studies indicate that such development is useful in predicting things such as an individual's health, life satisfaction, and degree of contribution to the society.

Four categories describe what changes, each in a different manner.
1) Stages are a description of successful performance on tasks of increasingly higher orders of hierarchically complexity. Stages exist because the tasks underlying stage of performance are hierarchically ordered. Both maturation and learning are necessary for stage change.
2) Maturation is driven by a biological clock. It consists of changes in hormones, neural development, such as in the frontal lobes, pairing of cells through cell death, dendritic growth, and cross-linking of molecules. The value of reinforcers and therefore motivation change with hormones.
3) At different periods and seasons of life, roles change. Periods and seasons are descriptions of roles that are socially designated for parts of life. They partially depend on maturation and greatly depend on culture. Knowledge, skills and expertise are learned but do not require stage change. They describe how much one learns at a given stage. Skills and knowledge can be developed through training, experience, teaching, etc.

This field stems originally from several threads of work within psychology. For example, Erik Erikson (1978) proposed a number of adult periods. Daniel Levinson (1978) had described a number of "seasons of life." Abraham Maslow proposed an adult needs hierarchy. Jean Piaget (Vuyk, 1980) came to agree that there were adult postformal stages beyond the stage of formal operations; his earlier theory had located an endpoint to the development of cognitive structures in the adolescent's acquisition of formal operations. John L. Horn (1970, 1979) found that crystallized intelligence, represented by such things as vocabulary size, increased in adulthood. Lawrence Kohlberg (1984) found that in early adulthood, some people come to think of moral, ethical and societal issues in multivarate terms (Systematic stage 11, the first postformal stage). They use multiple relations. During middle adulthood some people become principled reasoners about moral issues; for instance, they used abstract principles to relate systems of rights to systems of duties (Metasystematic stage 12, the second postformal stage). Likewise, Cheryl Armon (1984) found that by middle adulthood, some people could reason about interpersonal relationships at an order of complexity similar to that described by Lawrence Kohlberg. By 1978, research on positive adult development was growing at an extraordinary rate, and expanding upon these early threads in a number of directions. Summaries of some of that initial positive adult development research can be found in Commons, Richards, and Armon (1984), as well as in Alexander and Langer (1990). Four postformal adult stages of development beyond the formal stage have been discovered in a wide variety of domains. The total number of stages across the life span now stands at 15. Periods and Seasons have been described.

Now that such substantive bodies of knowledge are accruing about positive adult development, some researchers have turned to investigating methods to foster such development, rather than just describe it and/or measure it. For educators of adults in formal settings, this has been on the educational agenda in various forms already. More recently, efforts branched out to testing hypotheses about fostering positive adult development. This metods are used in organizational and educational setting. Some use developmentally-designed, structured public discourse to address complex public issues (Ross, 2007).

Ross, S. N. (2007). Effects of a structured public issues discourse method on the complexity of citizens' reasoning and local political development. Dissertation Abstracts International B, 68 (02). (UMI No. 3251492).